This invention relates to centrifugal blowers, and more particularly to an improved end construction for blower wheels and improved methods for both the manufacture and assembly thereof. More specifically, the invention relates to improvements in both the structure and method of manufacturing and assembling a blower wheel which reduce the amount of material required to construct the wheel and simplify the assembly operation while retaining the performance parameters of blower wheels manufactured and assembled by less efficient methods.
Blower wheels and methods of their assembly are well known in the art with a wide variety of blowers being commercially available. An example of a commercial blower wheel and its method of manufacture and assembly is disclosed in Wilken U.S. Pat. No. 2,537,805 commonly owned with the present application. In this patent, a plurality of blower blades are produced separately from a sheet of material. These blades have specifically configured flanges on their ends over which are folded end rings on the opposite ends of a double inlet blower wheel or at the open end of a single inlet blower wheel for securing the blades to the end rings.
An alternate method of constructing a blower wheel is disclosed in Wilken U.S. Pat. No. 2,628,419, also commonly owned with the present application, which discloses a blower wheel construction wherein the end rings have annular beads that are autogeneously welded to the ends of blades having straight outer edges. Further specific representative U.S. Patents disclosing blower wheel constructions and methods of manufacture and assembly include Wilken U.S. Pat. Nos. 2,651,830, 2,821,778 and 2,852,182, and Wentling U.S. Pat. Nos. 3,211,364, 3,165,258 and 3,253,318, all of which were owned by the predecessor of the assignee of the present invention.
In the past, blower wheel constructions and methods of manufacture and assembly, as disclosed above, have resulted in an uneconomical utilization of material in the form of scrap centers resulting from stamping of the sheet metal end rings utilized with those blower wheel constructions having end rings.
What is needed, therefore, is a blower wheel and a method of manufacture and assembly of blower wheels which will eliminate the scrap material produced by stamping the end rings from the material sheet, and which will simplify the assembly operation by assembling the blower wheel by means of assembly apparatus similar to that utilized in the assembly of a blower wheel having conventional sheet metal end rings. This is accomplished with the present invention by eliminating the end rings and replacing them with a pair of wire hoops for double inlet blower wheels, or a single wire hoop and a specially formed end member for single inlet blower wheels.